Abstract: A system and method for locating faults on multi-terminal power system transmission lines uses synchronized phasor measurements to accurately determine fault location and fault impedance regardless of fault type, fault resistance, and coupling to other adjacent power system transmission lines.

Abstract: A method of digitally correcting the raw output voltage from a Capacitive Voltage Transformer (CVT) with the intent to remove transient components impacting on transient accuracy of protection function. A typical CVT is represented using three parameters in the linear CVT model. A digital filter designed based on the three parameters and incorporating a dedicated mechanism to ensure numerical stability of the former. A method of self-adjusting the said filter based on system events and performed after the method has been deployed in the field and supplied from a specific CVT.

Abstract: A system and method for locating faults on multi-terminal power system transmission lines uses synchronized phasor measurements to accurately determine fault location and fault impedance regardless of fault type, fault resistance, and coupling to other adjacent power system transmission lines.

Abstract: A method for compensating for communications channel delay asymmetry in a current differential protection system includes determining an apparent sampling clock offset for a communications channel, the apparent sampling clock offset between a first sampling clock and a second sampling clock configured within the current differential protection system. An apparent global positioning system (GPS) clock offset is determined for the communications channel, the apparent GPS clock offset between a plurality of GPS time stamps corresponding to the first and said second sampling clocks. A compensated clock offset is determined by subtracting the apparent GPS clock offset from the apparent sampling clock offset so as to cancel out a channel asymmetry component of deviation in the apparent GPS and sampling clock off-sets.

Abstract: A method for determining transient errors in an unsynchronized, digital current differential transmission line protection system includes receiving a first current phasor measurement at a time, t, and receiving a second current phasor measurement at time t. The second current phasor is adjusted so as to account for a determined offset between a first sampling clock associated with the first current phasor measurement and a second sampling clock associated with the second current phasor measurement, thereby resulting in a rotated second current phasor measurement. A residual transient error is then obtained from the rotated second current phasor measurement and the first current phasor measurement.

Abstract: An integrated motor monitoring system collects, analyzes, and stores to database(s) on-line and off-line coordinated real-time motor data for industrial AC and DC motors. On-line coordinated real-time motor data from both on-motor sensors and remote sensors at a motor control center are collected simultaneously and processed. Off-line measurements are performed with integrated stimulus and measurement apparatus. Monitoring units at the motor and motor control center each collect specific data on the motor. The database provides current and historical data on the motor for analyses conducted at the motor or at the motor control center. Additionally the motor monitoring system has the capability of relating motor system or process events with motor performance.

Abstract: An algorithm for transforming data base schema information to object modeling notation utilizes meta models of the data base tables and the target object modeling notation respectively to bridge the gap between the data base schema representation and the object model representation. Detection of associations between classes of objects is performed for one-to-one, one-to-many, and many-to-many associations by analyzing unique key attributes. Once an object meta model is populated, the underlying object model may be displayed using existing software packages.

Abstract: A method and system for generating computer programs for queries by manipulating an object-oriented diagram. In the present invention, a query is specified for the object diagram. A series of transformations are performed on the object classes within the object diagram in accordance with the query. A revised object diagram representative of the query is then produced. Computer code is then automatically generated for the query from the revised object diagram. The code is used to prototype programs that query and/or update data stored in a database.

Abstract: Motor current and voltage waveforms are measured and converted to digitized current and voltage waveforms. A weighted discrete fourier transform is applied to the digitized current and voltage waveforms to obtain negative sequence current and voltage phasors; and the negative sequence current and voltage phasors are used to determine the existence of a turn fault. The use of the negative sequence current and voltage phasors can be performed by employing one of several techniques. In a first embodiment, an apparent negative sequence impedance is estimated by dividing the negative sequence voltage phasor by the negative sequence current phasor for comparison with a threshold negative sequence impedance. In a second, related embodiment, a current differential is estimated by dividing the negative sequence voltage phasor by a characteristic negative sequence impedance and subtracting the result from the negative sequence current phasor for comparison with a threshold current differential.

Abstract: A database shadowing system for performing data checkout/checkin operations. The system includes performing the steps of 1) identifying a data item stored in a database for editing, 2) copying the data item from the database to an active memory file thereby creating an active memory copy of the data item, 3) associating a tag with the active memory copy of the data item, changing a state of the data item 4) tag depending upon the edit operation performed on the active memory copy of the data item, and 5) saving any change made to the active memory copy of the data item by making the change to the database data item upon issuance of a save command, so that the data item tag of the active memory copy of the data item controls the manner of changing the database data item.

Abstract: A system and method for restructuring a product assembly utilizes a knowledge base of past product designs to identify to an expert, which components within the assembly are candidates for replacement with other components. By reducing the varieties of components in assemblies, the cost of manufacturing decreases. Data base management techniques are used to store and maintain data about the makeup of various assembly models and the criteria used to select the components for each assembly. Restructure candidates are identified by manipulating selection tables in such a way as to locate those criteria that have little effect on the choice of a given component. An expert then evaluates the possibility of replacing those components that are currently being used in those small number of cases where the aforementiond selection criteria with little decision making weight actually do determine selection of that particular component.

Abstract: A computer implemented process and apparatus for selecting components of an assembly from input design specifications and displaying the selected component to a system user is provided. The selected components can be displayed in one of many formats including in a bill-of-material format. In one embodiment, the apparatus includes selection means for selecting a component from input design specifications and display means for displaying the selected assembly components.

Abstract: A system and method for modeling digital circuit elements to enable verification of circuit design by formal proofs using a computerized theorem proving system, is disclosed.

Abstract: A digital frequency locked loop is disclosed for use with programmable signal processing apparatus wherein frequency locking is desired from staggered data samples. Sampling means are provided for sampling an input signal, at instants determined by the sampling signal, to provide N data signals from M cycles of the input signal wherein each data signal represents the magnitude of the input signal at the sampling instant. Signal processing means are provided for performing a unique approximation to the optimal mean square estimation analysis to provide a frequency deviation signal which is proportional to the difference in frequency between the sampling and input signals. The frequency deviation signal is used to modulate the period of the sampling signal such that the frequency of the sampling signal is maintained in constant proportion to the frequency of the input signal.

Abstract: Method and apparatus are disclosed for providing a sampling signal having a frequency which is maintained in constant proportion to the frequency of an input signal. The input signal is sampled at instants determined by the sampling signal to provide a plurality of data signals associated with one cycle of the input signal. A signal processor is adapted to receive first and second pluralities of data signals associated with first and second cycles of the input signal and to perform two discrete Fourier analyses to provide two phasor signals representing two voltage phasors of respective fundamental frequencies of the discrete Fourier transforms. The phasor signals are used to generate a difference signal indicative of the angle between the two voltage phasors and, therefore, proportional to the difference between the sampling frequency and the input frequency.

Abstract: Method and apparatus are provided for performing a plurality of digital signal processing functions wherein each said function is a unique combination of identical subfunctions. A plurality of operating units are provided wherein each operating unit is adapted to perform one said subfunction. Apparatus and method are disclosed for programmably configuring these operating units in a variety of serial combinations wherein each combination will perform a respective signal processing function.

Abstract: Disclosed is a method for overcoming one of the limiting factors in applying digital techniques to measuring analog signals over a wide dynamic range, namely, the uncertainty introduced into the measurement by noise and A/D conversion, particularly at low signal levels. A central feature of the technique is the filtering of the signal with a variable time constant digital filter, the time constant being a function of the measured signal in such way as to increase the effective resolution of small signals at the expense of an increased transient delay. For large signals, the time constant is reduced so that adequate transient response is provided when it is most needed and when there is already adequate resolution.

Abstract: Circuit protection and protective relay functions are provided by common circuit elements under the control of a single processor unit. Voltage and current values are obtained on a continuous basis and these values are continuously monitored within the processor to determine the electrical status of a protected power distribution system. Upon the occurrence of an overcurrent or undervoltage condition, the circuit is interrupted by operation of a circuit breaker trip solenoid causing the breaker contacts to open. When the overcurrent or undervoltage condition ceases to exist, the circuit breaker contacts could be closed by operation of a controlled relay. The ROM and RAM storage elements within the processor unit are continuously tested and the circuit breaker contacts are opened upon indication that the ROM or RAM element is nonfunctional.

Abstract: A generalized real-time thermal model of an induction motor produces values indicative of the transient and steady state temperature condition of the motor. Each of these values is compared with respective predetermined limits and power to the motor is removed when any value exceeds its respective limit in order to prevent damage to the motor.

Abstract: Samples from a first and second cycle of a system signal are used to generate discrete Fourier transforms for the respective first and second cycle. Multiplication of the discrete Fourier transform of the second cycle by the complex conjugate of the discrete Fourier transform of the first cycle produces a frequency deviation phasor whose angle with respect to the real axis is representative of the frequency deviation of the system signal from a predetermined reference frequency. Actual system frequency may be determined by obtaining the inverse tangent of the angle of the frequency deviation phasor with respect to the real axis.Apparatus for determining the frequency and frequency deviation of a system signal is disclosed as is a method and apparatus for determining frequency and frequency deviation of a system signal comprising a plurality of phases.